This invention relates to U.S. Pat. No. 4,223,751, issued Sept. 23, 1980, and entitled "High Speed Capacitance Apparatus for Classifying Pharmaceutical Capsules". In particular, the invention comprises an improvement to the machine disclosed in the aforementioned patent, which improvement enables the machine to classify capsules at an increased production rate.
The machine described in the aforementioned patent includes a hopper for holding a supply of capsules of a type and size commonly used in the pharmaceutical industry. The capsules in the hopper are conveyed to a turntable device which has a chute tangentially positioned along its circumference. Capsules are fed into the chute in a continuous stream, and the chute conveys the capsules into an air jet mechanism which propels them through a capacitive sensing device. The capacitance sensing device detects variations in weight of the capsules as they are propelled through the sensing device, and a mechanical deflector is energized to deflect capsules which fall outside of predetermined weight tolerances into a different trajectory than the trajectory of "good" capsules. The respective trajectories lead to collection receptacles wherein the "good" and "bad" capsules may be separately collected. The machine is designed to operate at very high rates of speed, and is capable of processing and weighing capsules at rates in excess of 2,500 capsules per minute.
While the aforementioned machine is capable of operating at high processing speeds, there has been a problem in the feed mechanism which is required to feed capsules in a continuous chain into the sensing device. Occasionally, a deformed or defective capsule, or a misaligned capsule, will move down the chute into the air jet propelling intake and will jam against the inlet of the air jet device and therefore stop the flow of the stream of capsules. In the past, when this circumstance occurred, it has been necessary for the operator to manually remove the nonuniform capsule to permit the capsule stream to continue. This has required continuous operator attention to the machine in order to facilitate maximum processing rate, and the time required for manual clearing of the problem capsules from the stream has resulted in an average processing rate slowdown.